The present invention generally relates to cellular mobile radio systems based upon the so called GSM standard (GSM--Global System for Mobile communication), and more particularly to a method for receiving in a GSM network data for supplementary services.
A GSM network basically comprises at least one base station system BSS including a base station controller BSC and base station transceivers BTS. The GSM network furthermore includes a mobile services switching centre MSC, a home location register HLR and a visitors location register VLR.
Each subscribing mobile station MS belongs to a HLR in a home network, wherein permanent subscriber data is stored. When a mobile station is registered in a MSC/VLR as a new visitor, that mobile station's HLR sends a copy of the relevant subscriber data to MSC/VLR. The data is sent via the CCITT #7 network from HLR to MSC/VLR. The procedures for this are described in the protocol MAP (Mobile Application Part--specified in ETSI GSM recommendation GSM 09.02). The data structure in MAP is described generally in accordance with ASN.1 (Abstract Syntax Notation). ASN.1 and its rules are specified in CCITT X.208/X.209.
Subscriber data in MAP is found defined in a general data type referred to as SubscriberData. This data type is of the "constructed" type, which according to ASN.1 means that it, in turn, contains new data types. The data type in SubscriberData which relates to data for supplementary services is called ProvisionedSupplementaryServicesprovisionedSupplementaryServices is, in turn, an SS-infolist which, according to the data structure in MAP, means that it is comprised of four different data types:
ForwardingInfo PA1 CallBarringInfo PA1 CUG-information PA1 SS-data
ForwardingInfo is a data type which describes call forwarding services in a general manner. CallBarringInfo is a data type which describes call barring services in a general way. CUG-information describes the more complicated data structure of a closed user group, while SS-data describes the data structure of other supplementary services that do not fall beneath any of the categories listed above.
In turn, these data types contain the data that is specific to respective supplementary services. For example, in the case of call forwarding services, there is a great deal of data which is common to these services, and consequently call forwarding data is generally described in ForwardingInfo. Thus, supplementary service data is to some extent general data, and to another extent data which is specific to a respective supplementary service.
The data types ForwardingInfo, CallBarringInfo and SS-data have one feature in common, which is that the first data type internally is the SS-code.
An SS-code is a data type which identifies a certain SS (Supplementary Service). Thus, all supplementary services in GSM are identified with the aid of an SS-code. An exception to this rule is the supplementary service CUG.
The aforesaid can be summarized more simply by saying that MAP contains sequences of what is here referred to as "containers" for supplementary service data. Respective "containers" always include a parameter which indicates the service to which the "container" content relates (this parameter is the "SS-code" in MAP), together with the data that varies from service to service. The parameter which identifies the intended service is always found in the same location internally within the "container", therewith enabling the data receiver to be identified in the same way, irrespective of the service entailed.
EP 454,647 describes the routing of calls made to mobile subscribers. The home exchange of the mobile subscriber maintains information which identifies the location of the mobile subscriber. When a call to a mobile is received in an interrogation exchange, the exchange requests from the home exchange information as to where the incoming call shall be routed. The home exchange, however, first asks the exchange where the mobile is assumed to be located to page the mobile. The result is reported to the home exchange, whereafter the home exchange informs the interrogation exchange of the location of the mobile.
U.S. Pat. No. 4,644,351 relates to the transmission of messages via a radio channel, from one of a plurality of fixed central locations with different coverage to remote units. Each remote unit is allocated a unique address and is connected to one of the central locations. When a message to a selected remote unit is accepted in a central location, it is stored in a paging site connected to the selected remote unit. The selected remote unit is localized by searching through a file which contains remote unit addresses together with the locations of those remote units which are not located in the area covered by their connected central locations. If the remote unit is not located in the radio covering area of the central location to which it is connected, the message and address are sent to the central location given in the address file.
U.S. Pat. No. 4,700,374 relates to mobile telephone localization. A plurality of mobile telephone exchanges supervise or monitor the presence of mobile telephone units in their own areas and are connected to a national centre. The national centre is able to receive queries concerning the location of mobile telephone units from each of the mobile telephone exchanges and transmit this information to all mobile telephone exchanges in the system, via a satellite. The information contained in the localizing information relates to the identity of the mobile telephone exchange and of the mobile telephone and is sent by the national centre to the mobile telephone exchange as an established query so as to enable the exchange to set-up a connection.
U.S. Pat. No. 4,752,951 describes a personal location system. A "PERSONAL LOCATION UNIT" includes "personal location units" and a base station. Information relating to subscriber locations is sent to a data base.
U.S. Pat. No. 4,901,340 relates to a technique which allows a roaming mobile telephone subscriber to receive a call directed to his home area while said subscriber is located in a foreign area outside his home area. The MTSO of the foreign area receives information to the effect that the subscriber in the foreign area wishes to receive calls directed to his home area. The subscriber is allocated a temporary directory number (TDN) for use in the foreign area.
U.S. Pat. No. 5,090,050 describes communication with radio telephones that belong to a radio telephone system when said telephones operate in another geographical area served by another radio telephone system. The radio telephone user sends via the telephone a signal which activates a database in the home system. The activation signal identifies the radio telephone and the other radio telephone system which serves the area in which the radio telephone is temporarily located. When receiving a call which is directed to the radio telephone, the database searches for the activation signal and the call is transferred to the other system via a land telephone line. Radio communication is then established between the other system and the radio telephone.